Pigmented naevi, which show the least tendency to growth or degenerative change, should be radically removed, as they not infrequently lead to carcinomatous and sarcomatous growths.

Ichthyosis.

(_Synonym:_ Fish-skin Disease.)

Give a descriptive definition of ichthyosis.

Ichthyosis is a chronic, hypertrophic disease, characterized by dryness and scaliness of the skin, with a variable amount of papillary growth.

At what age is ichthyosis first observed?

It is first noticed in infancy or early childhood. In rare instances it is congenital (ichthyosis congenita), and in such cases it is usually severe, and of a grave type; the children are, as a rule, prematurely born, and frequently do not survive many days or weeks.

What extent of surface is involved?

Usually the whole surface, but it is most marked upon the extensor surfaces of the arms and legs, especially at the elbows and knees; the face and scalp, in mild cases, often remain free.

Name the two varieties of ichthyosis usually described.

Ichthyosis simplex and ichthyosis hystrix, terms commonly employed to designate the mild and severe forms respectively.

Describe the clinical appearances of ichthyosis.

The milder forms of the disease may be so slight as to give rise to simple dryness or harshness of the skin (_xeroderma_); but as commonly met with it is more developed, more or less marked scaliness in the form of thin or somewhat thick epidermal plates being present. The papillae of the skin are often slightly hypertrophied. In slight cases the color of the scales is usually light and pearly; in the more marked examples it is dark gray, olive green or black.

In the severe variety--ichthyosis hystrix--in addition to scaliness there is marked papillary hypertrophy, forming warty or spinous patches.

This type is rare, and, as a rule, the surface involved is more or less limited.

Are there any inflammatory symptoms in ichthyosis?

No. In fact, beyond the disfigurement, the disease causes no inconvenience; in those well-marked cases, however, in which the scales are thick and more or less immovable, the natural mobility of the parts is compromised and fissuring often occurs. In the winter months, in the severer cases, exposed parts may become slightly eczematous.

Does ichthyosis vary somewhat with the season?

Yes. In all cases the disease is better in the warm months, and in the mild forms may entirely disappear during this time. This favorable change is purely mechanical--due to the maceration to which the increased activity of the sweat glands gives rise.

Is the general health affected in ichthyosis?

No.

What course does ichthyosis pursue?

Chronic. Beginning in early infancy or childhood, it usually becomes gradually more marked until adult age, after which time it, as a rule, remains stationary.

What is the etiology?

Beyond a hereditary influence, which is often a positive factor, the causes are obscure. It is not a common disease.

State the pathology.

Anatomically the essential feature is epidermic hypertrophy, with usually a varying degree of papillary hypertrophy also.

Mention the diagnostic features of ichthyosis.

The harsh, dry skin, epidermic and papillary hypertrophy, the furfuraceous or plate-like scaliness, the greater development upon the extensor surfaces, a history of the affection dating from early childhood, and the absence of inflammatory symptoms.

How is ichthyosis to be distinguished from eczema, psoriasis, and other scaly inflammatory diseases?

By the absence of the inflammatory element.

What is the outlook for a case of ichthyosis?

The prognosis is unfavorable as regards a cure, but the process may usually be kept in abeyance or rendered endurable by proper measures.

What treatment would you prescribe for ichthyosis?

Treatment that has in view removal of the scaliness and the maintenance of a soft and flexible condition of the skin.

In mild cases frequent warm baths, simple or alkaline, will suffice; in others an application of an oily or fatty substance, such as the ordinary oils or ointments, made several hours or immediately before the bath may be necessary. In moderately developed cases the skin is to be washed energetically with sapo viridis and hot water, followed by a warm bath, after which an oily or fatty application is made. In some of the more severe cases the following plan is often useful: The parts are first rubbed with a soapy ointment consisting of one part of precipitated sulphur and seven parts of sapo viridis; a bath is then taken, the skin wiped dry, and a one to five per cent. ointment of salicylic acid gently rubbed in.

Glycerine lotions, one or two drachms to the ounce of water, are also beneficial; as also the following:--

[Rx] Ac. salicylici, ...................... gr. x-xl Glycerini, ........................... [dram]ss-[dram]j Lanolin, Petrolati, .................. [=a][=a] [Oz]ss

In severe cases of ichthyosis hystrix it may be necessary, also, to employ caustics or the knife.

What systemic treatment would you prescribe?

Const.i.tutional remedies are practically powerless; occasionally some good is accomplished by the internal administration of linseed oil and jaborandi.